Valve element with molded resilient tip



May 20, 1969 E OR MYLES M MURRAY BY d mzjflwy a 0M ATTOR NEYS y 20, 1959M. N. MURRAY 3,445,089

VALVE ELEMENT WITH MOLDED RESILIENTv TIP Filed Dec. 8. 1965 Sheet Z of 23| yllllhfilfli v was ,v.

WW6 M ATTORNEYS United States Patent US. Cl. 251-358 4 Claims ABSTRACTOF THE DISCLOSURE A valve element having an elongated body with an endsocket and a metal pin with rubber molded about the head securely fittedin the body socket.

The present invention relates to valve elements of the type comprising arelatively rigid body and a tip of a resilient material applied theretoas the active sealing portion of the element. This invention is alsoconcerned with a method for the manufacture of such a valve element.

The rubber tipped needle valve element now being used in fuel inletvalve assemblies of carburetors for internal combustion engines is aspecific example of the indicated valve type and one with which thepresent improvements have been particularly concerned. Although arelatively recent introduction, this carburetor needle valve has becomewidely used and considerable attention is being given to possibleimprovement in the product itself, its performance characteristics, andtechniques for its manufacture, especially suited for very high volumeproduction. This invention is the result of such an effort and will beseen to provide improvement in all of the noted respects.

The invention thus provides a valve element comprising a relativelyrigid body and a resilient tip of such improved mechanical design as topermit a Wider choice of materials for its components. The presentcarburetor needle valve, for example, has a metal body and a tipanchored at one end which is made of a particular type of rubber whichis relatively hard and expensive, the heat and fluid resistantfluoroelastomer supplied by E. I. du Pont de Nemours & Co. under thename Viton being the standard compound. This rubber has been usedbecause of its resistance to swelling upon exposure to gasoline,although the hardness is somewhat greater than might be desired from thestandpoint of ability to seal notwithstanding dirt or impurities formingirregularities on the sealing surfaces. The new valve design permits autilization of softer rubber for enhanced sealing action; it is alsopossible with this design to employ materials other than metal for thebody member, such as a suitable rigid plastic, which cannot be used inthe conventional design.

The performance of such a valve element is influenced by the dimensionalrelationship of the tip to the body, with the noted carburetor inletvalve having a tip of conical shape and the critical relationship onthis order being-the concentricity of the tip with the body. The valveelements provided by this invention are improved in such regard and, inthe more specific reference example, exhibit a much better averageconcentricity of tip and body than the conventional elements. The newvalve element, moreover, is not susceptible to corking even with thenoted employment of softer rubber for the tip, and it can be used inhigh pressure applications in which the common rubber tipped needlevalve would be extremely likely to bind in the cooperable seat member.

The present manufacture of the rubber tipped carburetor needle valve andother valve elements of the same class involves the provision of a metalbody in the end of which a socket, usually threaded, is formed,inserting this body in a suitable mold assembly defining a tipformingcavity at such end of the body, and molding the rubber tip in the cavityagainst the body end and in the threaded socket to anchor the formedtip. The temperature and pressure conditions for rubber molding requirethat the body be made of metal in this procedure, and it will beappreciated that a solid rubber tip is produced. This process is limitedalso in that the size of the tip cannot exceed the diameter of theadjoining body end, and in the one operation there must be adequatecontrols to provide the desired concentricity of the tip and the bodyand also the finished overall length of the composite element. Thepresent invention provides a substantial departure from thisconventional procedure with the advantages of less rubber requirement,no practical limitation on the size of the tip resulting from the sizeof the body, reduced incidence of eccentricity of the tip relative tothe body, and exact length control of the finished product. The newmanufacturing process also provides greater capacity in a given moldassembly as compared to the usual practice, with consequent moreefiicient utilization of production equipment.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principle of the invention may beemployed.

In said annexed drawings:

FIG. 1 is an elevation of a carburetor needle valve in accordance withthe present invention;

FIG. 2 is a top plan view of such valve;

FIG. 3 is a fragmented longitudinal section of the tip and the valve onan enlarged scale;

FIG. 4 is an elevation of a headed pin employed as a component of thenew valve;

FIG. 5 is a top plan view of such pin;

FIG. 6 is a fragmented section of a mold assembly in which the headedpin is shown as an insert for molding rubber and the like about the headthereof;

FIG. 7 is an elevation of the pin having the rubber molded thereon, witha portion of the head in section;

FIG. 8 is a simplified and partly schematic illustration in section of amachine press employed for assembly of the tip formed by the pin andrubber with the body of the valve; and

FIG. 9 is a further elevation of a valve element having a rubber tip ofthe same configuration but of larger size.

Referring now to the drawings in detail, the valve ele ment illustratedin FIG. 1 is a carburetor float valve having an elongated metal body 10the major extent of which is generally of square cross-section but withthe corners 11 rounded as shown. The rounded corners 11 will engage thewall of the cylindrical fuel inlet passage of the carburetor, with thefiat sides 12 and the passage wall defining segmental passages for thefuel flow. At one end, this body is provided with a short cylindricalextension or neck 13 of reduced diameter, while the other end in theillustrated embodiment is undercut at 14 to receive an attaching clip.

At the neck end, there is a rubber tip 15 of conical shape, the base ofthe tip being disposed against the end face of the neck 13. This tip, asshown in FIG. 3, is formed by a headed pin 16 about the head of which abody 17 of rubber is molded. The valve body 10 is provided with a socket18 at this end of a length which is, for a purpose to be described,greater than the length or extent of the pin from the head to the otherend. The socket is cylindrical over its major extent, with its axiscoinciding with that of the body, but a conical enlargement 19 isprovided at the outer end, also for a purpose to be set forth below.

The pin 16 is made of a suitable metal, such as aluminum, preferably ina cold heading opeartion and the head is, more particularly, formed tocomprise a major part 20 in the form of a truncated cone and a minor orshoulder part 21 at the base of the conical part. The shoulder portion21 is cylindrical and of noticeably lesser diameter than the majordiameter of the conical part 20, while at the same time significantlylarger than the diameter of the body proper 22 of the pin. The other endof the pin is preferably beveled as shown at 23 and, as earlier noted,the length of the pin body 22 from the head from the shoulder 21 is lessthan the depth of the socket 1 8 formed in the end of the valve body.

It will be evident from a comparison of FIGS. 3 and 4 that the main headportion 20 of the pin is of the same form as the finished molded rubbertip but of smaller size, with the body 17 of the rubber enclosing thehead. The head of the pin thus serves as a rigid preform for the tip andnot only provides an added degree of rigidity but takes the place of asubstantial mass of the rubber which would be present in a solid rubbertip as in the conventional needle valve elements. It will also be seenthat the rubber is effectively locked to the pin 16 by the inwardcontinuation of the body behind the base of the main part 20 to theshoulder section 21.

It is preferred that the rubber be applied to the pin in moldingapparatus having a multiplicity of cavities for high volume production,and FIG. shows the character of such an assembly as to a single cavity,the others being identical. This assembly comprises a bottom plate 24 inwhich there is a hole 25 of a diameter fairly closely corresponding tothat of the body 22 of the pin, so that the pin can be positioned in theplate in the manner illustrated. The shoulder 21 overlies to anappreciable extent the upper surface of the plate 24 about the opening25 and, under the conditions of the rubber molding employed, theshoulder serves to seal this cavity forming surface of the plate againstrubber intrusion therebeneath and consequent flash formation. There is acenter plate 26 in the assembly having a hardened insert 27 in whichthere is formed a cavity 28 of the size and shape of the desiredfinished rubber tip, the axis of such cavity being in alignment withthat of the pin receiving bottom plate opening 25. A sprue passage 29provides communication from the top center of the cavity 28 to the upperface of the insert 27 which coincides with the top of the center plate26. The assembly is completed by a top plate 30 shown as spaced slightlyfrom the upper surface of the center plate 26 and, in accordance withknown molding techniques, a sheet of the particular rubber compositionon compound to be used is placed between the top and center plates andthe assembly is subjected to pressure and heat sufiicient to causerubber from the sheet to be injected through the sprue passage 29 andfill the mold cavity 28 completely about the head of the pin 16.

The tip thus produced is shown in FIG. 7 and FIG. 8 illustrates themanner in which such component is the body of the valve element. Againonly a single work station is shown in this last figure and it will beunderstood that production equipment will be used capable ofsimultaneously effecting a multiplicity of operations. In thisoperation, the body 10 is suitably supported in a substantially verticalcondition with its neck end uppermost and its other end preferablysupported in a base block 31 which is vertically adjustable within amachine support plate 32. It will be noted that the block 31 illustratedhas a slight concavity to provide correspondence with the somew atconvex end of the particular b dy 61- ment utilized, and the adjustmentdesired is shown as accomplished by a screw '33 threaded from theunderside in the support plate 32 and extending into a socket 34 inwhich the base 31 is closely but vertically adjustably disposed.Cooperating with this body support assembly is a ram 35 having at itsunderside a recess 36 closely corresponding to the rubber tip of the pinand with its axis aligned with the axis of the valve element body 10 inthe assembly. A pin 16 to which the rubber body has been molded isplaced to be guided into the body socket 18, with the diameter of thelatter being slightly smaller than the diameter of the pin body 22 toprovide significant interference. The ram 35 is then lowered to engagethe head of the pin in its recess 36, with this engagement assistingproper alignment of the pin, and the ram continues to descend with forceapplied suitable to drive the pin body 22 into the body 10 of the valveelement. It will be readily appreciated that this operation can beperformed in a standard punch press in which the ram 35 executes adefinite stroke and bottoms at a fixed distance above the support plate32 of the machine. Accordingly, the overall length of the needle valvecan be very exactly controlled by proper base support of the valve bodyrelative to the bottom position of the ram, and the adjustment providedas described permits this control to be realized with valves havingdifferent length specifications.

The bevel 23 at the end of the pin and the enlargernent 19 in the end ofthe body socket 18 assist in guiding the initial placement andpenetration of the former in the latter, and it will be seen from FIG. 3that the end plane diameter of the enlargement 19 is slightly greaterthan the diameter of the head shoulder portion 21, whereby there is adefinite clearance 37 between the two. This clearance is provided toassist in the noted length control of the valve, since it permits rubberto be distorted at this inner annular void in the event that aparticular combination of pin and body tends to exceed the desiredgauged length. In other words, a degree of more than usual compressionof the rubber can be tolerated in this manner without causing suchdeformation of the outer surface of the body as to render it unsuitablefor the intended use. It will also be noted from FIG. 3 in particularthat, since the rubber tip is appreciably smaller than the main valvebody, an assembly of mold plates of a given area can accommodateconsiderably more tips of the new pin form than valve bodies as in theconventional valve manufacture according to which such bodies must bepositioned in the assembly to receive the direct application of therubber to form the tips thereon. Moreover, the new valve utilizes twoseparately formed components in the pin and the body each of which willof course in quantity exhibit a variation of dimensions within specifiedtolerances, whereas the normal molding of the rubber tip to the metalbody as heretofore practiced necessarily causes any eccentricity in thebody always to appear in the tip. With the noted two formed parts,however, there is introduced for the first time the possibility ofoffsetting variations or slight deviations from the design dimensionsand it can be shown that a better average is thus obtained.

It has been proposed for some applications that the rubber tip of such aneedle valve be ground for still greater exactness, and the new tip isbetter suited for this operation if desired, since the preform rigidityprovided by the pin makes the tip less susceptible to deformation undergrinding pressure than the solid rubber tip. This added rigidity is alsosignificant in use of the valve in a high pressure environment, such asin an air solenoid valve in which substantial pressure is exerted behindthe needle tending to force the assembly into the cooperable seat. Wherethe tip is entirely of rubber, there is a very definite likelihood thatthe deformation would be such to bind forcibly the tip in the seat, atendency which is much less likely if at all with the new tip of thisinvention.

A related advantage is the fact that a softer rubber than usuallyemployed for the purpose can be satifactorily used in the new tip,including tips of valve elements which will be exposed to gasoline suchas the carburetor inlet valves. An example of the rubber suitable forthe purpose is Buna N elastomer, which is an inexpensiveacrylonitrile-butadiene latex copolymer commercially available under thetrade name Hycar of the B. F. Goodrich Company. The backing andreduction in rubber mass provided by the pin permit this use withoutdanger of excessive swelling or corking, and the greater softnessdefinitely assists in improved sealing by reason of accommodation toimpurities on and irregularities in the sealing surfaces.

As shown in FIG. 9, the new valve element can also readily be utilizedin a form in which the rubber tip 15' is of greater diameter than theend 13 of the valve body to which it is attached. This of course resultsfrom the fact that the tip is formed independently of the body andsubsequently united therewith, whereas in the standard needle the bodymust serve as a closure for the mold cavity and accordingly limits thesize of the tip.

I, therefore, particularly point out and distinctly claim as myinvention:

1. A resilient tip valve element, comprising an elongated element bodyhaving a socket in one end, and a separatively formed composite tipsecured to the element body at said one end, said tip including a metalpin having a head and a body extension of relatively reduced size, andresilient sealing material molded about the head of the pin, with thepin body extension projecting from the sealing material and secured inthe socket of the element body to provide a valve element of apredetermined length.

2. A valve element as set forth in claim 1, wherein the element body isof rigid nonmetallic composition.

3. A valve element as set forth in claim 1, wherein the resilientsealing material overlies the end of the element body about the socket,and there is an interior annular void in the valve element about the pinbody extension at the projection of the same from such socket to permitthe resilient sealing material to be distorted in such void when saidpin body extension is secured in the socket of the element body asaforesaid.

4. A valve element as set forth in claim 1, wherein the head of themetal pin is of a solid geometric form having significant axial extent,and the sealing material is of generally corresponding shape.

References Cited UNITED STATES PATENTS 1,886,721 11/1932 OBrien.2,194,961 3/ 1940 Walker 251-357 XR 3,027,134 3/1962 Nichols 251358 XR3,191,212 6/1965 Heiss et al 1642 3,326,520 6/ 1967 Guenther 25 l358FOREIGN PATENTS 4,713 3/ 1915 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner.

